Traveling overhead cranes

ABSTRACT

Portable overhead traveling crane comprises bridge beam having its ends supported on trucks and hoist beam suspended from bridge beam by block and cable system. Hoisting machinery is mounted on hoist beam which also has means, such as hook, for engaging a load. Method of erection and dismantling is by securing blocks to, and removing blocks from, the bridge beam while hoist is at ground level.

[451 Oct. 15, 1974 United States Patent [1 1 Droniek et al.

FOREIGN PATENTS OR APPLICATIONS 3 027 025 3/1962 Tantlinger.....................l.. 3,452,964 7/1969 Blbeault 3,550,788 12/1970 C S mm m mo r mm E m HX h EA Vr. Ow m m H MW T .m H H U W Hill; Edwin Henry Zimmerman, Harrisburg, both of Pa.

[73] Assignee: Aycock, llnc., Camp Hill, Pa.-

6/1962 Germany 254/188 202,734 4/1959 Sweden............................... 254/184 [22] Filed: Mar. 2, 1970 Appl. Nb; 15,438

Primary Examiner-James B. Marbert Assistant Examiner lames L. Rowland Attorney, Agent, or Firm-Frederick Raring Cm B e 46 6 B H 2 2 5 2 l 2 l 2 0 St Um nu 55 [57] ABSTRACT Portable overhead traveling crane comprises bridge beam having its ends supported on trucks and hoist beam suspended from bridge beam by block and cable [56] References Cited UNITED STATES PATENTS system. Hoisting machinery is mounted on hoist beam which also has means, such as hook, for engaging a load. Method of erection and dismantling is by securing blocks to, and removing blocks from, the bridge beam while hoist is at ground level.

4 Claims, 10 Drawing Figures a m m 1 W m m n mm h.1 6 r C 6 g nh w v. 1 S O NMUAB 437 94556 89999 111.11 39428 003043 9402 ,0 2 77464 453 9 2222 mmu mmgm SHEU l W 9 INVENTORS L QSTEQ maxmwm Dezowc K EDwm Hemwg Z\MMERMAN BY M/ Film 081 I 51974 SHEET 2 Q? 9 mmmw l 51914 mums saw a as 9 PATENTEB I 5574 3.841.495 sum ear 9 PAIENTED 1 5874 SHEETS 9 1 TRAVELING OVERHEAD CRANES I BACKGROUND OF TI IE INVENTION This invention relates to traveling overhead cranes. The invention is herein disclosed in an embodiment comprising a portable overhead crane of the type commonly used to transport extremely heavy loads. However, many of the features of the invention can be employed to advantage in permanent crane installations.

A typical portable traveling overhead crane in accordance with previously known engineering practice comprises spaced apart rails mounted on elevated runway girders, a bridge beam extending between the rails, carriages or trucks mounted on the rails to transport the bridge beam the length of the runway, and hoisting machinery mounted on the bridge beam. For a large capacity crane, say 700 tons, the bridge beam, including the hoisting machinery, the cable, and the blocks, can be expected to weigh as much as 80 to 100 tons. The runways for cranes of this type are 190 feet or more above ground level and the bridge beam and hoisting machinery must be raised up to the level of the bridge beam during erection and lowered when the crane is dismantled. It can, therefore, readily be appreciated that the assembly of the bridge beam and the hoisting machinery to the static frame structure of a portable overhead crane is a time-consuming and an expensive operation. In fact, it is common practice in the portable traveling crane art to partially disassemble the hoisting machinery from, and reassemble the hoisting machincry to, the bridge beam when the crane is dismantled and erected. These assembly and disassembly procedures are time-consuming and costly but are necessary in order to avoid the necessity of lifting or lowering the bridge beam as a unit. Additionally, the cables must be reeved through the blocks when the crane is set up and must be removed from the blocks when the crane is dismantled, operations which further increase costs of erection and dismantling.

It is also common practice in the portable overhead traveling crane art to mount the hoisting machinery on the bridge beam in a manner such that the bridge beam is heavily loaded midway between its ends. This arrangement results in the highest possible bending stresses being induced in the bridge beam, thereby requiring a relatively heavy member for this part of the crane.

In accordance with the instant invention, an additional girder or beam, referred to as a hoist beam, is suspended from the bridge beam by suspending means connected to the bridge beam adjacent to its ends. The hoisting machinery is mounted on the hoist beam and the load is engaged by a suitable hook connected to the hoist beam. This arrangement, in accordance with the invention, results in substantial time savings when the crane is erected or dismantled for the reason that the hoisting machinery need not be raised up to, or lowered from, the level of the bridge beam. A further advantage is achieved in that the bridge beam is efficiently loaded, in accordance with a preferred embodiment, so that its size need not be excessive. Also, the entire hoist beam may be transported by truck or rail to the site of the lifting operation and assembled thereto without the necessity of removing any of the hoisting machinery or disassembling the hoisting machinery.

It is an object of the invention to provide an improved overhead traveling crane. A further object is to provide an improved portable overhead traveling crane in which the hoisting machinery is mounted on a beam suspended from the bridge beam. A further object is to achieve a reduction in the time required for erecting and dismantling a portable overhead traveling crane. A still further object is to achieve a reduction in the stresses induced in a bridge beam of a portable traveling overhead crane without a reduction in the load capacity of the crane. A still further object is to provide an improved method of erecting and dismantling an overhead crane.

These and other objects of the invention are achieved in a preferred embodiment thereof which is briefly described in the foregoing abstract, which is described in detail below, and which is shown in the accompanying drawings in which:

FIG. 1 is a perspective view of a preferred form of portable overhead traveling crane in accordance with the invention looking from one end of the crane.

FIG. 2 is an orthographic end view of the crane of FIG. 1 illustrating the manner in which the hoist beam can be transported to the crane frame.

FIG. 3 is a fragmentary side view looking in the direc tion of the arrows 3-3 of FIG. 2.

FIG. 4 is a side view of the hoist beam.

FIG. 5 is a semi-diagrammatic perspective view of the hoist beam.

FIG. 6 is an irregular sectional view taken substantially along the lines 66 of FIG. 5.

FIG. 7 is a diagram illustrating the manner in which the cable is reeved or laced from the drums through the block and sheave assemblies on each side of the hoist beam.

FIG. 8 is a fragmentary side view showing the control means for the drum brake of one of the hoists.

FIG. 9 is a side view showing a transporting pallet by means of which the cables and blocks can be removed from the hoist beam and transported separately.

FIG. 10 is a perspective view of a storage drum which is mounted on the transporting pallet.

THE DISCLOSED EMBODIMENT Referring now to FIG. I, the disclosed embodiment of the invention comprises spaced apart runway girders l2, 12', which are supported on the upper ends of columns 2, 4, 6, 2', 4', 6, by means of pedestals 14. The pedestals are supported on rocker bearings 16 on the truncated pyramidal upper ends 17 of the columns. The lower ends of the columns are also truncated and pyramidal as indicated at 11 and have rocker bearings 10 on their undersides which rest upon suitable pedestals 8 supported on the ground. Guy wires (not specifically shown) are employed to stablize the columns as required. The columns may be fabricated from tubing, as shown, and are advantageously sectional to facilitate transportation to, and from, an operation site. Transverse beams 20, 22 are secured to the ends of the runway girders 12, 12', in order to stablize the runway structure. As is apparent from FIG. 1, the front transverse girder 20 extends beyond the runway girders as indicated at 24 and 24. This arrangement provides a wider clearance between the columns 2, 2', in order to accommodate oversize loads.

A bridge beam 30, comprising spaced apart box girders secured to each other, extends between the runway girders and has reduced end portions 32, 32' which are supported on trucks 34, 34'. The wheels 36, 36', of these trucks are supported on rails 28 on the upper surfaces of the runway girders 12, 12', and the wheels 38 being suitably driven by motors 40 through couplings 42. A hoist beam or hoist support 44 is disposed beneath the bridge beam 30 and suspended by means of cables generally indicated at 46, 46.

Two sets of hoisting equipment 48, 48' are provided on the upper side of the hoist beam 44 to shorten and lengthen the cables 46, 46'. Since the hoisting mechanisms on the left and right hand ends of the hoist beam and the associated block and tackle assemblies are substantially identical, a description of one will suffice for both. Accordingly, only the hoisting equipment, the blocks, and the cables on the left hand side of the hoist beam ,as viewed in FIG. 1 will be described in detail and the same reference numerals, differentiated by prime marks, will be used to identify corresponding structural elements on opposite ends of the hoist beam 44.

Referring now to FIG. 3, the upper or bridge beam block assembly 50 for the cable 46 comprises a rectangular box-like sheave block 54 having parallel sides 56 and center web plates 58. A plurality of large diameter sheaves 60, identified specifically in FIG. 7 by the reference numerals 60a60h, are mounted on a shaft 62, which extends between sidewalls 56 and through web 58 adjacent to the upper end of the block 54. A plurality of smaller diameter sheaves 64 are similarly mounted on a shaft 66 beneath the larger diameter sheaves. The lower sheave block 68, the hoist beam block, has parallel sides 70 mounted between the girder sections 44 of the hoist beam and has center web plates 72. A plurality of smaller diameter sheaves 74a-74h are mounted on a shaft 76 which extends between the sides of the block and through the center web section. A corresponding number of larger diameter sheaves 78a-78h are mounted on a shaft 80 which extends between the sides of the block beneath the shaft 76. An equalizing sheave 86 is mounted on a stub shaft 88 in the lower portions of the lower sheave block, the axis of this shaft extending normally of, and beneath, the axes of the shaft 78. The upper and lower sheave blocks are removably secured to the bridge beam and the hoist beam respectively by means of suitable pins 79, 81, 82, 84 which can be removed for purposes of disassembling these blocks and the cable from the beams in a manner which will be described below.

The suspension system shown in FIG. 3 comprises a compound sheave and block system which is reeved in the manner shown in FIG. 7. A pair of drums 90a, 90b mounted on a common shaft 94 are provided to which the ends of the cable are attached. The cable fall 460 extends from the drum 900 over a compensating sheave 92a mounted on a shaft 130a to the outside large diameter sheave 78a of the hoist beam block 68. The cable runs from the sheave 78a to the sheave 64a which is the outside left hand small diameter sheave of the bridge beam block 54 and is reeved rightwardly over the small diameter sheaves 64a-64d, 74a-74d of the left hand sides of the two blocks. From the small diameter sheave 74d, which is the hoist beam block, the cable extends to the sheave 60d which is against the left hand side of the web 58 of the bridge beam block 54. The cable is reeved leftwardly from sheave 60d over the large diameter sheaves of the bridge beam and hoist beam blocks. The last sheave of this series of runs is the sheave 60a and the cable extends from sheave 60a to the equalizing sheave 86 then to the right hand diameter sheave 60h of the bridge beam block. The cable is reeved from the sheave 60h around the large diameter sheaves of the bridge beam block and hoist beam block as indicated until it arrives at the large diameter sheave 60e of the bridge beam block. The cable extends from this sheave to the small diameter sheave 74e of the hoist beam block and is then reeved rightwardly around the upper and lower small diameter sheaves as indicated until it arrives at the small diameter sheave 64h which is on the right hand side of the bridge beam block. The cable extends from this sheave to the outside large diameter sheave 78h of the hoist beam block thence over a compensating sheave 92b to the drum b at 46b.

The cable is thus reeved from the drums 90a, 90b inwardly towards webs 58, 72 over the small diameter sheaves then outwardly over the large diameter sheaves to the equalizing sheave 86. This arrangement ensures that all of the cable runs extending between sheaves of the bridge beam block and hoist beam block will be shortened or lengthened by the same amount when the drums are rotated. Since the drums are mounted on a common shaft 94, the same amount of rotation is imparted to both drums when the shaft is rotated.

The compensating sheaves 92a, 92b and the shafts 130a, 13012 may be of the known type available from LeBus International Engineers, Inc. of Longview, Texas, and from the several overseas companies associated with LeBus, U.S.A. Each compensating sheave traverses the shaft on which it is mounted during spooling; also, the attitude of the sheave is changed during traversal in a manner such that the cable is spooled perpendicular to the axis of the drum at all times. Since spooling systems of this type are well known to the art, the compensating sheaves and shafts are shown diagrammatically in the drawing and are not described in detail in the description presented below of the structural details of the drums.

The suspension system shown in FIG. 7 is particularly advantageous in the practice of the instant invention in that it provides a high mechanical advantage and is relatively compact, particularly as regards the hoist beam block, the compensating sheaves, and the drums. The location of the compensating sheaves 92a, 92b on the opposite side of the drums from the side on which the hoist beam block is located and the fact that the cables extend from sheaves 78a, 78h beneath the drums to the compensating sheaves thence to the drums minimizes the distance between the extreme members (the compensating sheaves and the hoist beam block) of these parts as is apparent from FIG. 4. As is also apparent from FIG. 4, the space available on the hoist beam for the hoisting equipment is somewhat limited so that compact and efficient positioning of the hoisting equipment on the hoist beam is essential. The high mechanical advantage achieved is advantageous in that it permits the use of smaller and lighter actuating means for the drums without loss of lifting capacity.

As shown best in FIG. 6, the drums 90a, 90b are defined by collars 91 and one side 95 of a brake 134, described below. The collars 91 are mounted on a rotatable shaft 94, the central collars 91 being supported by connical plates 93 which are also secured to the shaft 94. This shaft is rotatably supported at its ends by suitable bearings 96 on a stationary shaft 99, the ends of which extend transversely of the hoist beam and are supported in the enlarged upper ends of pedestals 98, secured to the upper surfaces of the girder sections 45 of the beam. The shaft 94 is rotated in either direction by a radial hydraulic motor 102 acting through a drive train which rotates a large diameter gear 104 fixed to the shaft 94. The gear 94 meshes with a pinion 106 keyed or otherwise secured to a shaft 108. The left hand end of this shaft, as viewed in FIG. 6, is rotatably supported in bearing means 110 in the pedestal 98 and the right hand end of this shaft is supported in bearing means 112 mounted in the upper end of a bearing support plate 121 which extends upwardly from a transversely extending girder section 47. A large diameter gear 114 is mounted on the right hand end of shaft 108 and meshes with a pinion 116 which is keyed or otherwise secured to a shaft 118. Shaft 118 is rotatably supported in suitable bearings in a bearing support plate 119 which also extends upwardly from girder section 47. Shaft 118 is coupled by means of a resilient coupling 123 to a brake 120 which is mounted on the output shaft of the previously identified radial hydraulic motor 124.

The resilient coupling 123 serves to dampen any unexpected shock which may be imposed on the drive train and may be of the type available from Holset Manufacturing Co., Ltd., and in the United States from Koppers Company, Inc., Coupling Department. Couplings of this type are described in US. Pat. Nos. 2,621,493, 2,873,590 and other issued United States Patents. For a crane having a capacity of 700 tons, the hydraulic motor 102 may be a Staffa Type B200 which is available in the United States from Double A Products Co. of Manchester, Michigan.

Brake 120 may be a conventional band type brake in which a brake band bears against the periphery of a brake drum, control being achieved by suitable hydraulic means. The brake 120 is similar in many respects to an additional emergency brake 134 which is described in detail below.

Hydraulic fluid under pressure is supplied to motor 102 through either of two hydraulic lines 122, 124 which extend to a hydraulic pump 126, FIG. 41, the reservoir for which is provided in one of the transverse girder sections 67 of the hoist beam. Motor 102 is driven in either direction, depending upon which of the lines 124, 122 is pressurized by the pump. The hydraulic pump 126 is driven by an electric motor 128 mounted beside the pump. Motor 128 runs continuously, control of the drums being effected by means of suitable valves (not specifically shown) which control the direction of flow of hydraulic fluid to the hydraulic motor 102 and the intensity of the flow. For a 700 ton crane, the pump 126 may be a reciprocating piston swash plate pump of the type manufactured by Sundstrand of LaSalle, Illinois, and the electric motor may be a conventional 75 HP AC motor.

The previously identified compensating sheaves are mounted on shafts 130a, 130b, the ends of which are supported on U shaped brackets 132, 133 which, in turn, are fixed to the upper surfaces of the sections 45 of the hoist beam. As will be apparent from FIG. 4, the bracket 132 for the shaft 130, and the shaft 130', is nested within the bracket 133 which supports the shafts 130b, 13%. As previously noted, the cable falls extend from the sheaves 78a, 78h diagonally beneath the drums 90a, 90b to the compensating sheaves then to the drums.

While the brake 120 will ordinarily be used to check the descent of the hoist beam, it is desirable to provide an additional fail safe brake means for safety purposes. To this end, a large diameter brake drum 134 is fixed to the shaft 94 and a brake band 101 bears against the periphery of this drum. Control of this auxiliary braking system is achieved by means of a lever (FIG. 8) pivotally mounted on a pin 152 which, in turn, is mounted in a bracket 154. The bracket is mounted on the upper surface of the adjacent girder section 45 beside the brake drum. A compression spring means 156 is interposed between the end of lever 150 and the surface of a supporting plate 159 mounted on the surface of the girder. A hydraulic piston-cylinder 158 ad 15 jacent to the spring means has its piston rod pivotally connected at to lever 150 and is pivoted at its lower end to the supporting plate 159. This piston is normally pressurized in its upper end so that the piston rod holds the lever 150 in the position shown against the force exerted by the spring means 156. One end 136 of the brake band 101 is connected by a fitting to the pivot pin 152. The other end 156 of band 101 is connected to lever 150 beneath pivot pin 152.

Piston-cylinder 158 is integrated into the hydraulic control system by suitable circuitry in a manner such that when the hydraulic system is functioning normally, the upper end of this piston cylinder is pressurized and the lever is maintained in the position shown against force of spring means 156. Under these circumstances, the band 101 is not in close engagement with the surface of the brake drums. In the event of a failure or malfunction in the hydraulic system, the pressure is relieved on the upper side of the piston and the spring means 156 urges the lever upwardly causing the end 156 of the band to be pulled along an arcuate path away from the drum. The brake band is thus clamped against the drum to prevent sudden and uncontrolled descent of the hoist beam.

The hoisting machinery on the right hand side of the hoist beam is a substantial mirror image of the hoisting machinery on the left hand side. Separate hydraulic controls may be provided for each set of hoisting machinery although it is also possible to provide a single control for both sets to operate them in synchronism if desired.

The work piece or load is engaged by means of a suitable hook 140 pivotally mounted on a pin 142 extending between the girder sections 45 intermediate their ends. Additional pins 146, 146' are provided in order to permit spreading of the load and suspending it from two axes near the ends of the girder.

The operation of raising and lowering a given load will be apparent from the foregoing description. The load is engaged by a suitable sling or the like suspended from the hook 140 and the hydraulic motors are actuated to rotate the shafts 94, 94' in the desired direction. To raise the hoist beam and the load, cable is spooled onto the drums from each end of the hoist beam block assemblies. Lowering of the load, of course, merely requires reversal of the hydraulic motors.

Some of the principal advantages of the instant invention stem from the ease with which the crane can be erected or dismantled. Referring to FIG. 2, and assum ing that the crane is about to be dismantled after a lifting operation has been completed, the hoist beam is lowered from the position shown in FIG. 2 until it comes to rest on the central bed 148 of the trailer shown. Thereafter, the pins holding the upper block assemblies 50, 50 are removed and the blocks are lowered from the bridge beam while the cable between the sheaves is spooled onto the drums. Lowering of the blocks 54, 54' may be achieved by a conventional boom crane which is commonly used when a high capacity overhead crane is being assembled or dismantled. After all of the cable of both of the upper block assemblies has been wound onto the drums of the hoists 48, 48 the block assemblies themselves can be suitably stowed above the hoist on a temporary wooden frame.

The entire hoist beam and all of the hoisting equipment can then be transported to the site of the next lifting operation by the truck.

The advantages of the instant invention can readily be appreciated if the relatively simple dismantling procedure outlined above is compared with present engineering practice in the portable overhead crane art. In accordancewith present practices, the hoisting equipment is mounted on the bridge beam and the load is engaged by a hook block suspended centrally from the bridge beam by cables. The hoisting equipment is quite heavy and the bridge beam must, therefore, be relatively stronger than a bridge beam for a crane in accordance with the instant invention. Furthermore, the prior art method of loading of the bridge beam intermediate its ends, that is, midway between runway girders, results in a much higher stress level in the bridge beam than is developed where the load is suspended adjacent to the ends of the bridge beams in accordance with the instant invention. Finally, the bridge beam and hoisting equipment are of a weight such that boom cranes or other equipment required to raise the bridge beam to the level of the upper surfaces of the runway girders is not generally available when a prior art portable crane is being erected. It thus becomes necessary in accordance with prior art practice to disassemble the hoisting equipment from the bridge beam, raise the bridge beam up to the runway girders and position it on these girders, and then raise the hoisting equipment, piece by piece, up to the level of the bridge beam and mount it thereon. This involves unreeving all of the cable from the blocks of the hoisting equipment and the hook block and rereeving the cable when the crane is erected.

The advantages of the invention are strikingly apparent from a consideration of the weights of some of the components of a high capacity (about 700 tons) portable crane. Where the crane is designed and constructed in accordance with the principles of the instant invention, the bridge beam need weigh no more than about tons, because of the fact that the load is suspended from the bridge beam adjacent to its ends and the stresses in this beam are maintained at a relatively low level as a result of this end loading. The hoist beam, including the hoisting machinery but not including the cable and blocks, will weigh about 54 tons and the cable and blocks will weigh an additional 24 tons. As explained above, this hoist beam need not be raised up to the level of the runway girders in accordance with the invention but is in effect utilized to assemble itself to the runway beam. In accordance with prior art practice, equipment having comparable weight must be lifted up to the level of the bridge beam and be mounted thereon before the crane is ready for operation.

Under some circumstances, it may prove desirable to remove the cable and blocks from the hoist beam during transportation of this beam from one site to another. For example, where the hoist beam is being transported over highways, the weight limitations on the truck may preclude transporting the entire hoist beam assembly as a unit. Under such circumstances, the two cables and four blocks (which have a combined weight of about 24 tons when the crane capacity is 700 tons) can be removed from the beam and transported on pallets 162 of the type shown in FIG. 9. A divided drum 164 having sides 167 and a central dividing flange 166 is mounted on the pallet intermediate the ends of the pallet on pedestals 168. Suitable supports, in the form of channel sections and blocks, 172, 174, 176 are provided on the pallet to snugly support the hoist beam block 68 and the bridge beam block 54 beneath the drum with the equalizing sheave 86 disposed adjacent to the drum.

When one of the sets of blocks and the associated cable are being prepared for shipment separate from the hoist beam 44, the blocks are mounted on the pallet as shown in FIG. 9. The bight 178 of the cable is removed from the equalizing sheave and positioned in a notch in the central flange 166 of the drum. The drum is then rotated in the direction of the arrow by an auxiliary power means to draw the cable from the hoist beam drums 91 through the two blocks 54, 68 and spool the cable onto the storage drum 164. The cable ends are not drawn through the blocks but are tied off on either the pallet or the lower sheave block 68. In order to protect the section of the spooled cable immediately adjacent to the notch 170, battens 180 are mounted on the cylindrical surfaces of the drums. These battens do not extend for the full widths of the drums but are discontinuous to provide space for the first turn of cable spooled onto the drums. After this first turn of cable is on the drum, the cable is wound over the battens which thus protect the first turn of cable.

The foregoing relatively simple procedure thus results in a substantial reduction of the weight of the hoist beam during shipment if a reduction is required. Installation of the cable on the hoist beam at a new operation site merely requires that the cable ends be attached to the hoist beam drum 91 and that the drums be rotated to draw the cables from the storage drum 164, through the blocks and onto the hoist beam drums. The cable is not unreeved and rereeved but remains reeved through the blocks while the blocks and cable are on the pallet 162.

Under some circumstances, the invention can be employed to advantage in permanent as well as portable overhead crane structures. For example, where the crane must be installed in a building or shed having a relatively low ceiling, and where runways means, such as a ledge on the wall of the building, are located adjacent to the roof, there will not be sufficient room to accommodate the hoisting machinery on the upper end of the runway girder. Under such circumstances, a hoist beam in accordance with the instant invention having the hoisting machinery thereon can be provided. A further example of the use of the invention on a permanent crane installation is provided by the situation where a single heavy load must be handled in a shed or power house which is beyond the capacity of the existing permanent crane. Under these circumstances a hoist beam in accordance with the invention can be suspended from a bridge beam supported on the runway girders of the permanent crane structure, temporary strengthening of these runway girders being provided if required.

Modifications of the invention within the scope of the appended claims will be apparent to those skilled in the art. Under some circumstances, suspension systems other than the system shown in the drawing may be employed, and, in fact, it may prove desirable to suspend the hoist beam centrally from the runway beam with suitable stabilizing auxiliary suspensions being provided it" necessary. The advantages of ease of assembly of the hoist beam to the crane would be realized with this arrangement and it would not be necessary to raise the hoisting machinery up to the level of the runway beam during the erection of the crane. While the disclosed embodiment shows separate hoisting engines and mechanisms for the two ends of the hoist beam, it is within the scope of the invention to provide a single hoisting engine with suitable suspension system to raise and lower the beam during operation of the single hoisting engine.

We claim as our invention:

1. A portable traveling overhead crane comprising parallel spaced-apart runway girders, column means supporting said runway girders at a predetermined level above ground level, a truck on each of said runway girders, and a bridge beam extending between said runway girders and having its ends supported on said trucks,

a hoist beam disposed beneath said bridge beam,

first and second bridge beam blocks removably mounted on said bridge beam adjacent to said trucks,

first and second hoist beam blocks removably mounted on said hoist beam adjacent to the ends thereof,

first and second cables reeved through said blocks whereby said hoist beam is suspended from said bridge beam,

first and second cable drum means on said hoist beam, each of said cable drum means comprising a pair of side-by-side drums mounted on a common shaft, each of said cables having one of its ends connected to one of said drums of one of said cable drums means and the other one of its ends connected to the other of said drums of the same cable drum means,

each of said first and second bridge beam blocks and hoist beam blocks comprising a compound block having a plurality of larger diameter sheaves and a plurality of smaller diameter sheaves, and an equalizer sheave adjacent to each of said hoist beam blocks, the said cable for each of said sets of blocks extending from one of said drums over an outside large diameter sheave of the associated hoist beam block thence to the outside small diameter sheave of the associated bridge beam block, thence alternately over one half of the small diameter sheaves of the said hoist beam blocks and bridge beam blocks, thence being reeved outwardly over the larger diameter sheaves of said bridge beam and hoist beam blocks and extending to said equalizing sheave, first and second drive means on said hoist beam for rotating said drums, and means on said hoist beam for engaging a load which is to handled by said crane, whereby, the provision of said cable drum means and said drive means on said bridge beam permits disassembly of said hoist beam from said crane at ground level by removal of said bridge beam blocks from said bridge beam and two-blocking of said bridge beam blocks and said hoist beam blocks; and permits assembly of said hoist beam to said crane at ground level by raising said bridge beam blocks to said bridge beam and securing said bridge beam blocks to said bridge beam.

2. A crane as set forth in claim 1 wherein said equalizing sheaves are mounted on said hoist beam blocks.

3. A crane as set forth in claim 2 including compensating sheave means for each of said drums, said compensating sheave means being mounted on said hoist beam inwardly of said cable drum means.

4. Hoisting and load holding means for use with an overhead traveling crane of the type comprising a bridge beam, first and second truck means supporting the ends of said bridge beam, and means for guiding said truck means and said bridge beam along a predetermined path, said hoisting and load holding means comprising:

a hoist beam first and second block and tackle means, each of said block and tackle means comprising a first block removably secured to said hoist beam adjacent to one end thereof, a second block, securing means for securing said second block to said bridge beam, and cable means reeved through said first and second blocks, and

hoist means on said hoist beam, said hoist means comprising first and second hoist drum means, said first hoist drum means being disposed adjacent to said first block of said first block and tackle means and said second hoist drum means being disposed adjacent to said first block of said second block and tackle means, each of said hoist drum means comprising a pair of side-by-side drums, said cable means of each of said block and tackle means having one end extending to each of said drums, and

compensating sheave means for each of said drums, said compensating sheave means for each of said hoist drum means being adjacent to its respective hoist drum means and inwardly, on said hoist drum, from its respective hoist drum means whereby,

said hoist beam can be assembled to said crane by locating said hoist beam parallel to, and beneath, said bridge beam, raising said second blocks to the level of said bridge beam while withdrawing said cable means from said hoist means, securing said second blocks to said bridge beam adjacent to the ends thereof, and actuating said hoist means to raise said bridge beam. 

1. A portable traveling overhead crane comprising parallel spaced-apart runway girders, column means supporting said runway girders at a predetermined level above ground level, a truck on each of said runway girders, and a bridge beam extending between said runway girders and having its ends supported on said trucks, a hoist beam disposed beneath said bridge beam, first and second bridge beam blocks removably mounted on said bridge beam adjacent to said trucks, first and second hoist beam blocks removably mounted on said hoist beam adjacent to the ends thereof, first and second cables reeved through said blocks whereby said hoist beam is suspended from said bridge beam, first and second cable drum means on said hoist beam, each of said cable drum means comprising a pair of side-by-side drums mounted on a common shaft, each of said cables having one of its ends connected to one of said drums of one of said cable drums means and the other one of its ends connected to the other of said drums of the same cable drum means, each of said first and second bridge beam blocks and hoist beam blocks comprising a compound block having a plurality of larger diameter sheaves and a plurality of smaller diameter sheaves, and an equalizer sheave adjacent to each of said hoist beam blocks, the said cable for each of said sets of blocks extending from one of said drums over an outside large diameter sheave of the associated hoist beam block thence to the outside small diameter sheave of the associated bridge beam block, thencE alternately over one half of the small diameter sheaves of the said hoist beam blocks and bridge beam blocks, thence being reeved outwardly over the larger diameter sheaves of said bridge beam and hoist beam blocks and extending to said equalizing sheave, first and second drive means on said hoist beam for rotating said drums, and means on said hoist beam for engaging a load which is to handled by said crane, whereby, the provision of said cable drum means and said drive means on said bridge beam permits disassembly of said hoist beam from said crane at ground level by removal of said bridge beam blocks from said bridge beam and two-blocking of said bridge beam blocks and said hoist beam blocks; and permits assembly of said hoist beam to said crane at ground level by raising said bridge beam blocks to said bridge beam and securing said bridge beam blocks to said bridge beam.
 2. A crane as set forth in claim 1 wherein said equalizing sheaves are mounted on said hoist beam blocks.
 3. A crane as set forth in claim 2 including compensating sheave means for each of said drums, said compensating sheave means being mounted on said hoist beam inwardly of said cable drum means.
 4. Hoisting and load holding means for use with an overhead traveling crane of the type comprising a bridge beam, first and second truck means supporting the ends of said bridge beam, and means for guiding said truck means and said bridge beam along a predetermined path, said hoisting and load holding means comprising: a hoist beam first and second block and tackle means, each of said block and tackle means comprising a first block removably secured to said hoist beam adjacent to one end thereof, a second block, securing means for securing said second block to said bridge beam, and cable means reeved through said first and second blocks, and hoist means on said hoist beam, said hoist means comprising first and second hoist drum means, said first hoist drum means being disposed adjacent to said first block of said first block and tackle means and said second hoist drum means being disposed adjacent to said first block of said second block and tackle means, each of said hoist drum means comprising a pair of side-by-side drums, said cable means of each of said block and tackle means having one end extending to each of said drums, and compensating sheave means for each of said drums, said compensating sheave means for each of said hoist drum means being adjacent to its respective hoist drum means and inwardly, on said hoist drum, from its respective hoist drum means whereby, said hoist beam can be assembled to said crane by locating said hoist beam parallel to, and beneath, said bridge beam, raising said second blocks to the level of said bridge beam while withdrawing said cable means from said hoist means, securing said second blocks to said bridge beam adjacent to the ends thereof, and actuating said hoist means to raise said bridge beam. 